Torsion spring balancing means for pivoted doors



June 27, 1967 A. J. MACAULAY 3,327,700

TORSION SPRING BALANCING MEANS FOR PIVOTED DOORS 2 Sheets-Shem 1 Filed May 13, 1966 INVENTOR.

ANGUS I MACAULAI AW/K HtS ATTORNEY June 27, 1967 A. J. MACAULAY 3,327,700

TORSION SPRING BALANCING MEANS FOR PIVOTED DOORS 2 Sheets-Sheet Filed May 15, 1966 FIGB INVENTOR ANGUS I MACAULAX BY WA ms ATTORNEY United States Patent 3,327,700 TORSION SPRING BALANCING MEANS FOR PIVOTED DOORS Angus J. Macaulay, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed May 13, 1966, Ser. No. 550,003 Claims. (Cl. 126-191) This invention relates to the art of counter-balanced doors and more particularly to an improved torsion spring type counter-balancing means for use with such doors. This invention is useful with many types of counter-balanced, pivoted doors. However, it will be described with relation to the drop door for a domestic oven as it was initially designed for such use and appears to have particular utility in that art.

For about the last decade many domestic ovens have been provided with easily removable doors. In recent times manufacturers have provided many different door models for the same model range. Some are plain, some have special decorative trim, some are solid and some have oven windows. It will be appreciated that all these various doors do not have the same weight for a given door size. This weight variation creates a problem in providing a single door counter-balancing means which is built into the oven body and which will be satisfactory for any one of the possible door choices. This problem has been heightened by the movement to ship ovens from the factory minus their door, and to ship the doors separately to the dealers in quantity so that they can install the particular one chosen by any individual purchaser. The solution to this problem is to build the counter-balancing means into each oven door, rather than having the means built into the oven body. This was done in my co-pending application Ser. No. 417,141, filed Dec. 9, 1964, now Patent No. 3,263,674, and assigned to General Electric Company. That application discloses an adjustable, selfcontained door counter-balancing system utilizing torsion bars. The counter balancing means disclosed therein operates in an entirely satisfactory manner; however, it occupies a substantial amount of space, is fairly difficult to adjust and is somewhat complicated to manufacture.

It is an object of this invention to provide an improved, door mounted, adjustable counter-balancing system.

Another object of this invention is to provide such an improved counter-balancing system which utilizes torsion springs.

A further object of this invention is to provide such an improved counter-balancing system which is compact in size and easily adjusted, both at the time of door assembly as well as later.

The present invention, in accordance with one form thereof, is.embodiedin a hinged door that is capable of swinging between a substantially vertical closed position and a substantially horizontal fully open position. Counter-balancing means is provided for the door to retard the opening action of the door as it moves away from its vertical position and to facilitate the closing action of the door as it moves toward itsvertical position. The counterbalancing means includes a support bar mounted for pivotal movement about its own axis within the door structure and a hinge lever mounted on one end of the bar adjacent a side edge of the door for pivotal movement with the bar. The hinge lever projects outwardly of the door in a plane generally perpendicular to the inner surface of the door. The door frame of the oven body includes a bearing means which is adapted to be engaged at all times by an edge of the hinge lever. The counterbalancing means further includes a torsion spring which is connected to the other end of the support bar by a holding link mounted on the bar for pivotal movement Patented June 27, 1967 ice therewith. The other end of the torsion spring is connected to the door by a spring retainer. Thus, the torsion spring holds the hinge lever against the bearing means and deflection of the hinge lever by the bearing means during opening movement of the door exerts a tensioning force on the spring. The holding link and support bar are constructed so that the link may be mounted on the bar in different angular positions relative thereto and the spring retainer is made selectively adjustable. Thus, the initial tension of the spring may be varied as for basically different doors and the tension may thereafter be adjusted for various models of each basic door.

My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a front elevational view of an appliance such as a domestic oven showing a front-opening access door with parts broken away to illustrate an improved, self-contained door counter balancing means utilizing a torsion spring and embodying the present invention.

FIGURE 2 is a fragmentary side elevational view of the door taken along the line 2--2 in FIGURE 1.

FIGURE 3 is a fragmentary side elevational view of the oven front as taken along line 3-3 of FIGURE 1 but with the door moved to its fully open position.

FIGURE 4 is a persepctive view of a counter-balancing means of FIGURE 1.

Turning now to a consideration of the drawings, and in particular to FIGURE 1, there is shown for illustrative purposes an electric range 10 having a top cooking surface or cooktop 11 with a plurality of surface 'heating elements 12 and an oven 13 located beneath the cooktop 11 for performing both baking and broiling operations. The oven has inner walls forming an oven cavity and these walls are formed by a box-like oven liner 14 (shown better in FIGURE 3) which hasa front-opening, that is adapted to be closed by an oven door 15. This door 15 is a front-opening, drop door that has a door handle 16 adjacent its top edge, and quick connect hinge means 17 along its bottom edge.

Looking at FIGURE 3, the hinge mean 17 is shown as including a hinge bracket 18 that is fastened at its inner leg 19 to some suitable portion of the oven body such as door frame 20 and extends outwardly of the body through a suitable slot 21 formed in the front wall of the door frame. The outermost end of hinge bracket 18 is formed with a hook member 22 that establishes an upwardlyfacing slot 23 for receiving a hinge pin 24 that is mounted on the lower portion of door 15 (as best seen in FIGURE- 1). Thus, at this stage of the design, it will be seen that it is possible to lift the hinge pin 24 of the door 15 in and out of the slot 23 of the hinge bracket 18. However, in the absence of this lifting force, the door will remain connected to the oven by the quick-connect hinging means 17.

Viewing-now particularly FIGURES 1 and 2, it Will be seen that the over door 15 is made up of two sheet metal panels; namely, an outer panel 25 and an inner panel 26. The outer panel 25 is of rather simple configuration, while the inner panel 26 has a large central, rectangular embossment 27 which is adapted to telescope within the door opening or throat of the oven liner 14. This large embossment 27 is filled with thermal insulation 28 such as fiberglass or the like so as to retain much of the heat generated within the oven cavity and prevent its escape from the oven to the kitchen. There is a tab and slot connection 29 at the lower edge of the door between the outer panel 25 and the inner panel 26, while the top of the door is held together with fastening screws (not shown) that extend through the inner panel of the door and into the door handle 16 as is the general practice in the art.

Looking at FIGURE 1, each door hinge pin 24 is supported from a vertical channel member 30 and 30 respectively, that are fastened to the inside surface of the inner door panel 26 as by welding or the like. The channel members 30 and 30 also form the mounting brackets of the counter-balancing means and are utilized to mount the counter-balancing means in the door. It will be seen in FIGURE 1 that the counter-balancing means is duplicated on each side of the door. It is conceivable under certain circumstances that a single counter-balance system or means would suffice using only one channel member, but the preferred embodiment of the present invention utilizes duplicate biasing means with one on each side of the door.

As seen particularly in FIGURE 4, channel member 30 includes a base 31, an outer side wall 32 and an inner side wall 33. The channel 30' is a mirror image of the channel member 30 and the remaining parts of the counter-balancing means are duplicates whether they are used on the right or the left hand side of the door. Therefore, the same number will be used in reference to a particular part, whether it is being used on the right or on the left side. A support bar 34 is mounted on the channel member by means of low friction bearings 35, with one of the bearings being received in an appropriate opening in each of the side walls 32 and 33 of the channel member. In this manner, the support bar 34 is firmly held longitudinally by the channel member and, at the same time, is allowed to rotate or pivot about its own axis. The outer end of the support bar terminates adjacent the one side edge of the door 15 while the other end extends a substantial distance inwardly between the inner and outer panels of the door. A hinge lever 36 is mounted on the outer end of the support bar 34. To this end, the support bar 34 is of a non-circular cross section, at least at the ends thereof, in the illustrated embodiment being of hexagonal cross-section. A slot 37 is formed in the inner panel 26 of the door so that the hinge lever 36 may project from the door in a plane that lies substantially perpendicular to the inner surface of the door.

. A torsion spring 38 is mounted around the inner end of support bar 34 and has a sufficient inside diameter under all normal operating circumstances so as not to bind on the bar. One end 39 of the spring is connected to the inner end of support bar 34 by means of a holding link 40 as is best seen in FIGURE 4. To this end holding link 40 includes an opening 41 which is of a size and shape complentary to support bar 34 for a sliding fit on the support bar 34 and a slot 42 which receives the end 39 of spring 38. With the arrangement of parts as so far described the end 39 of spring 38 may move longitundinally with respect to the support bar 34 while it is constrained for pivotal movement with the support bar. The other end 43 of spring 38 is positioned to continuously engage a spring retainer 44. It will be noted that the end 43 of the spring engages the upper surface 45 of the spring retainer and that the upper surface is wide so as to allow some longitudinal movement of the spring. Additionally, the spring retainer includes a ledge or edge 46 extending upwardly from the upper surface so as to prevent the end 43 of spring 38 from sliding off spring retainer 44.

Viewing FIGURE 4, and assuming that spring retainer 44 is constrained from downward movement, it will be seen that clockwise rotation of support bar 34 and hinge lever 36 will cause end 39 of spring 38 to be rotated in such a manner as to exert a tensioning force on spring 38. This tensioning of the spring will also cause a slight change in length of the spring; however, the ends of the spring are so mounted as to allow for longitudinal movement of the spring. Conversely, a counterclockwise movement of support bar 34 and hinge lever 36 will allow the spring 38 to loosen and release some of the tension stored therein. In addition to allowing longitudinal movement of the spring as its tension varies, the sliding fit of link 40 on support bar 34 permits the use of various length springs with one common length bar.

My invention utilizes this winding and unwinding of the torsion spring 38 to resist the opening of door 15 and to assist the closing of the door so as to provide a counterbalancing means. To this end, hinge lever 36 is provided with a cam surface 47 along its top edge. The distal end of hinge lever 36 is provided with a hook portion 48 for engagement with a bearing member such as a sound absorbing roller 49 of nylon or the like material that is rotatably supported between hinge bracket 18 and door frame 20 by some suitable means such as pin 50. Engagement of the hook portion 48 with the bearing means 49 serves as a stop means to limit the outward swinging action of door 15 to a substantially horizontal fully open position such as that seen in FIGURE 3. However, a stop member may be added adjacent the bearing means or roller 49 to be engaged by the hinge lever hook portion 48 so as to relieve the bearing means of such a heavy strain. The bearing means or roller 49 has an additional function, namely, to serve as a low friction bearing member in engagement with cam surface 47 of the hinge lever 36 for deflecting the lever in a clockwise direction (as seen in FIGURES 3 and 4) as the door is lowered from its vertical to its horizontal position so that tension may be exerted on the spring 38 to build up energy within the spring to be used in assisting with the raising of the door back from the horizontal to the vertical position. To this end the bearing means need not be a roller bearing; any low friction, Wear resistant member will sufiice.

The cam surface 47 has two other principal portions;

namely, a closing surface 51 and a broil-stop surface 52-53. The closing surface 51 cooperates with the bearing 49 to exert a holding force against the door in its closed position. The broil-stop surface 52-53 forms a V-shaped notch in which the bearing 49 may be temporarily seated to hold the door in a partially open position of about 15 angul-arity with respect to the oven front. This is designed as the broil position for all-owing the free flow of room air through the oven cavity when the top heating element or broil element is energized at full wattage.

It will be understood that, during the process of assembling the counter-balancing means in the door, different initial tensions may be exerted on spring 38 so that the same parts may be utilized to construct counter-balancing means for a number of different basic doors. This is accomplished first by engaging end 43 of spring 38 with spring retainer 44 and then rotating spring end 39 and holding link 40 so that the holding link 40 is in different angular relationships with regard to support bar 34 before inserting opening 41 in holding link 40 over the end of the bar. However, it is unlikely that this initial adjust. ment will be satisfactory for all of the different door model a pair of mounting pins 55 and 56 that in turn are mounted in channel member '30. A pair of low friction washers 57 and 58 are supported on the mounting pins 55 and 56 respectively and bear against a surface 59 of the spring retainer 44 so as to hold the spring retainer against side wall 33 of the bracket member. Thus, spring retainer 44 is held against all but a vertically sliding motion (as seen in FIGURE 4).

In order to restrain the spring retainer against unwanted vertical motion and to adjust the vertical position of the spring retainer an adjusting screw 60 is provided. The adjusting screw 60 is threadedly received in a mounting clip 61 that in turn is attached to the inner door panel by some suitable means such as welding. The inner end of the screw bears against the lower surface of spring retainer 44. The initial tension of spring 38 is suflicient to keep spring retainer 44 adjacent screw 60 and the screw holds the spring retainer 44 against movement by spring 38 as the door is opened, so that the tension in the spring is increased during door opening. Additionally, by adjusting screw 60, the basic tension of spring 38 may be adjusted to compensate for differences in weight of different models of the same basic door and to provide for individual user preference. To this end, the lower edge of door 15 is provided with openings 62 so that the screw for each counter-balancing means may be easily adjusted.

It is also important for the housewife to be able to remove the door 15 without the use of special tools and without any mechanical complications. This function is provided by a releasable latch pin 62 as best seen in FIG- URES 1 and 3. The latch pin is slidable under the hinge lever 36 when the oven door 15 is in its substantially fully open position of FIGURE 3 so as to engage behind a shoulder 63 of the lever and thereby immobilize the counter-balancing means. When this is done it is possible to partially close the door -15 and in so doing the hinge lever 36 will shift away from engagement with roller 49. Thus the door may be lifted bodily from the hinge brackets 18. The releasable latch pin 62 is provided with a handle portion 64 which allows the manipulation of the latch pin. A suitable spring 65 is connected at one end to the latch pin 62 and at its opposite end to a flange 66 of inner door panel 26 by means of a hook portion '67. The reason for having the spring 65 is because the handle 64 cooperates with a curved slot 69 in the base 31 of each of the channel members 30 and 30 and extends through an appropriate opening 70 in the inner panel 26 of the door. Hence the handle 64 of the latch pin 62 cannot be shifted from one of its extreme positions to the other except by the movement of the handle 64 through its detent slot against a biasing force provided by spring '65, as will be understood by those skilled in the art.

The foregoing is a description of an illustrative embodiment of the invention and it is my intention in the appended claims to cover all forms which fall within the scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, a door for closing the opening, hinge means adjacent the bottom edge of the door for removably securing said door to the front wall for swinging movement between a vertical closed position and a substantially horizontal open position, a counter-balance means including at least one hinge lever having a pivotal support means on said door adjacent one side edge thereof, said hinge lever lying in a plane that extends generally perpendicular to said door, a bearing means mounted adjacent the front wall of the oven for engagement by said hinge lever, a torsion spring, first means connecting one end of said spring to said lever for pivotal movement therewith, and second means connecting said spring to said door so that an opening movement of said door exerts a tensioning force on said spring by the act of said bearing means deflecting said hinge lever.

2. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, a door for closing the opening, hinge means adjacent the bottom edge of the door for removably securing said door to the front wall for swinging movement between a vertical closed position and a substantially horizontal open position, a counter-balance means including at least one bar pivotally mounted in said door, a hinge lever mounted on said bar for pivotal movement therewith, said hinge lever lying in a plane that extends generally perpendicular to said door, a bearing means mounted adjacent the front wall of the oven for engagement by said hinge lever, a torsion spring, first means connecting one end of said spring to said bar for pivotal movement therewith, and

second means connecting said spring to said door so that an opening movement of said door exerts a tensioning force on said spring by the act of said bearing means deflecting said hinge lever.

3. An oven assembly having walls defining an oven cavity that has an opening in a front wall thereof, a door for closing the opening, hinge means adjacent the bottom edge of the door for removably securing said door to the front wall for swinging movement between a vertical closed position and a substantially horizontal open position, a counter-balance means including at least one bar located within said door, support means pivotally mounting one end of said bar on said door adjacent one edge thereof, a hinge lever mounted on said one end of said bar for pivotal movement therewith, said hinge lever lying in a plane that extends generally perpendicular to said door, a bearing means mounted adjacent the front wall of the oven for engagement by said hingle lever, a torsion spring, a spring holding link connecting one end of said spring to the other end of said bar for pivotal movement therewith, and a spring retainer connecting the other end of said spring to said door so that an opening movement of said door exerts a tensioning force on said spring by the act of said bearing means deflecting said hinge lever.

4. A structure as recited in claim 3 wherein said spring holding link is adapted to be mounted on said bar in different angular positions relative thereto so that a predetermined initial tension may be exerted on said spring.

5. A structure as recited in claim 3 wherein said spring retainer is adapted selectively to be movable to adjust the tension of said spring so as to compensate for doors of different weights.

6. A removable door structure, a body having a vertical Wall with a door opening therein, a pivoted door adapted to close the opening, a pair of first hinge members rigidly secured to said body adjacent the bottom edge of the opening, a pair of second hinge members carried by the lower edge of the door and adapted to engage with said first pair of hinge members and serve as quick release pin and slot hinge means for said door, a counter-balance means including at least one bar pivotally mounted in said door, a hinge lever mounted on said bar for pivotal movement therewith, said hinge lever lying in a plane that extends generally perpendicular to said door, a bearing means mounted adjacent the front wall of the oven for engagement by said hinge lever, a torsion spring, first means connecting one end of said spring to said bar for pivotal movement therewith, and second means connecting said spring to said door so that an opening movement of said door exerts a tensioning force on said spring by the act of said bearing means deflecting said hinge lever.

7. A removable door structure as recited in claim 6 with the addition of an adjustable latch means carried by the door and engageable with the hinge lever to immobilize said counter-"balance means to facilitate the separation of said hinge means and the removal of said door.

8. A removable d-oor structure, a body having a vertical wall with a door opening therein, a pivoted door adapted to close the opening, a pair of first hinge members rigidly secured to said body adjacent the bottom edge of the opening, a pair of second hinge members carried by the lower edge of the door and adapted to engage with said first pair of hinge members and serve as quick release pin and slot hinge means for said door, a counter-balance means including at least one bar located within said door, support means pivotally mounting one end of said bar on said door adjacent one edge thereof, a hinge lever mounted on said one end of said bar for pivotal movement therewith, said hinge lever lying in a plane that extends generally perpendicular to said door, bearing means mounted adjacent the front wall of the oven for engagement by said hinge lever, a torsion spring, a spring holding link connecting one end of said spring to the other end of said bar for pivotal movement therewith, and a spring retainer 7 a connecting the other end of said spring to said door so that an opening movement of said door exerts a tensioning force on said spring by the act of said bearing means deflecting said hinge lever.

'9. A structure as recited in claim 8 wherein said spring holding link is adapted to be mounted on said bar in different angular positions relative thereto so that a predetermined initial tension may be exerted on said spring.

10. A structure as recited in claim 8 wherein said spring retainer is adapted selectively to be movable to adjust the tension of said spring so as to compensate for doors of different weights.

References Cited UNITED STATES PATENTS McCormick 126-190 Mills 126194 Stoligrozy et al 126191 Pollock 126-191 KENNETH w. SPRAGUE, Primary Examiner. 

1. AN OVEN ASSEMBLY HAVING WALLS DEFINING AN OVEN CAVITY THAT HAS AN OPENING IN A FRONT WALL THEREOF, A DOOR FOR CLOSING THE OPENING, HINGE MEANS ADJACENT THE BOTTOM EDGE OF THE DOOR FOR REMOVABLY SECURING SAID DOOR TO THE FRONT WALL FOR SWINGING MOVEMENT BETWEEN A VERTICAL CLOSED POSITION AND A SUBSTANTIALLY HORIZONTAL OPEN POSITION, A COUNTER-BALANCE MEANS INCLUDING AT LEAST ONE HINGE LEVER HAVING A PIVOTAL SUPPORT MEANS ON SAID DOOR ADJACENT ONE SIDE EDGE THEREOF, SAID HINGE LEVER LYING IN A PLANE THAT EXTENDS GENERALLY PERPENDICULAR TO SAID DOOR, A BEARING MEANS MOUNTED ADJACENT THE FRONT WALL OF THE OVEN FOR ENGAGEMENT BY SAID HINGE LEVER, A TORSION SPRING, FIRST MEANS CONNECTING ONE END OF SAID SPRING TO SAID LEVER FOR PIVOTAL MOVEMENT THEREWITH, AND SECOND MEANS CONNECTING SAID SPRING TO SAID DOOR SO THAT AN OPENING MOVEMENT OF SAID DOOR EXERTS A TENSIONING FORCE ON SAID SPRING BY THE ACT OF SAID BEARING MEANS DEFLECTING SAID HINGE LEVER. 